Field of the Invention
The present invention relates to an electronic component with a semiconductor chip and a method for fabricating the electronic component.
In the fabrication of electronic components with semiconductor chips, rewiring plates are often employed, which are glued onto the active surface of the semiconductor chip such that a through-hole remains clear. The through-hole serves for providing a bond channel, so that after the gluing process, bond wires can be bonded from contact surfaces on the semiconductor chip to contact terminal pads on the rewiring plate. After the bond connections are glued and attached, the bond channel (i.e. the through-hole in the rewiring plate) is covered with a plastic compound.
As miniaturization of the semiconductor chips progresses and integration increases, the number of contact surfaces on the chip tends to rise. But the component size should not grow as chips become smaller. Therefore, the density of interconnects per area on the rewiring plate increases. In order to accommodate more contact terminal pads in the bond channel, they can be configured in two or more rows, although this requires a wider bond channel and thus reduces the area available for the rewiring tracks.
It is accordingly an object of the invention to provide an electronic component with a semiconductor chip and a method for producing the electronic component which overcome the above-mentioned disadvantages of the prior art apparatus and methods of this general type.
In particular, it is an object of the invention to design an electronic component with a semiconductor chip that makes it possible to produce reliable bond connections in order to overcome the disadvantages of the prior art.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for fabricating an electronic component, which includes steps of: providing a semiconductor chip having an active front side with semiconductor structures and contact surfaces configured such that a first portion of the contact surfaces extend in two parallel rows, and at least a second portion of the contact surfaces extend in one row; providing a rewiring plate with an oblong through-hole forming a bond channel and with a rewiring plane facing away from the semiconductor chip; providing the rewiring plane with contact terminal pads, rewiring lines, and external contact surfaces; fastening the semiconductor chip on the rewiring plate, such that the contact surfaces of the semiconductor chip are positioned in the through-hole of the rewiring plate; producing bond connections between the contact surfaces on the semiconductor chip and the contact terminal pads on the rewiring plate; and filling the through-hole with a plastic compound to embed the bond connections.
In accordance with an added mode of the invention, the method includes steps of: providing the bond connections with bond wires that cross longitudinal sides of the through-hole and providing the bond wires with approximately uniform wire lengths.
With the foregoing and other objects in view there is also provided, in accordance with the invention, an electronic component, including: a semiconductor chip having an active front side with semiconductor structures and contact surfaces; a rewiring plate having a rewiring plane with contact terminal pads; and bond connections between the contact surfaces on the active front side and the contact terminal pads. The rewiring plane faces away from the semiconductor chip. The active front side of the semiconductor chip is fastened on the rewiring plate. The rewiring plate is formed with an oblong through-hole for receiving the bond connections. The through-hole has a first portion in which the contact surfaces extend in two parallel rows. The through-hole has at least one additional portion, for example, a second portion in which the contact surfaces extend one row.
This configuration of contact surfaces makes possible a partly narrowed contour of the through-hole and thus makes more space available at the narrowed locations for terminal pads of the rewiring plane.
In a first embodiment of the invention, the contact surfaces are arranged in two parallel rows in a central first portion and in only one row in peripheral second and third portions, respectively.
In the center first region of the through-hole, the contact surfaces of the semiconductor chip extend in two parallel rows, because more space is available on the rewiring plate for contact terminal pads. In contrast, in the peripheral second and third portions, the contact surfaces extend in only one row, because here there tends to be less space available for contact terminal pads. The contact terminal pads in electrical contact with the contact surfaces extending in second and third portions thus have sufficient space in this configuration.
In an alternative embodiment of the invention, the contact surfaces are arranged in one row in the central first portion and in two parallel rows in the peripheral second and third portions, respectively.
This way, there is less space available on the rewiring plate for contact terminal pads in the peripheral second and third portions, where the contact surfaces of the semiconductor chip extend in two parallel rows. On the other hand, in this embodiment the contact surfaces extend in only one row in the middle first portion, so that more space is available for contact terminal pads at this location. The contact terminal pads which are in electrical contact with the contact surfaces extending in the first portion therefore have sufficient space in this configuration.
An inventive embodiment provides that the semiconductor chip includes edge sides and a back side opposite the active front side. It is further provided that the contact surfaces on the active front side have a structure and configuration to which the through-hole of the rewiring plate is adapted.
This inventive embodiment has the advantage that, in the peripheral regions, sufficient area remains between the through-hole and external contacts, such that conductive tracks of the rewiring structure can be led between them.
According to another embodiment of the invention, the contact surfaces on the semiconductor chip are electrically connected to contact terminal pads on the rewiring plate by bond connections, and the contact terminal pads are electrically connected by rewiring lines and external contact surfaces of the electronic component.
The particular advantage of this embodiment is that fast and inexpensive electrical connections can be produced by using the bond connections. The through-hole in the rewiring plate is advantageously a bond channel.
According to another embodiment of the invention, the through-hole in the rewiring plate has an oblong contour. A central first region of the through-hole corresponds to the contact surfaces that are arranged in the central first portion, and peripheral second and third regions of the through-hole respectively correspond to the contact surfaces arranged in the second and third portions. It is further provided that the through-hole has a narrowed contour in the second and third regions compared to its contour in the first region.
The advantage of this embodiment is that sufficient space is available for the rewiring structure that is arranged on the rewiring plate between contact terminal pads and the external contacts. The contact terminal pads can thus be constructed large enough that reliable bond connections can always be installed on them.
In another inventive embodiment, the bond connections including bond wires on the long sides of the through-hole have approximately uniform wire lengths, which advantageously enables rapid and reliable bonding. The approximately equal bond wire lengths also guarantee an approximately uniform height of the bond connections and thus a sufficiently flat electronic component.
According to an inventive embodiment, the contact terminal pads respectively adjoin the long sides of the through-hole and have approximately equal area dimensions. This guarantees a reliable bond connection on any contact terminal pad at any time.
A typical rewiring plate thickness is between 150 xcexcm and 300 xcexcm. The purpose of the rewiring plate is to transmit electrical signals and to supply currents of the semiconductor chip from the microscopic contact terminal pads to macroscopic external contact surfaces via conductive tracks. In this context, the term xe2x80x9cmicroscopic dimensionsxe2x80x9d refers to structures that can be measured only under a light microscope, and the term xe2x80x9cmacroscopicxe2x80x9d refers to structures that can be recognized with the naked eye.
According to another embodiment of the invention, the rewiring plate includes a fiber-reinforced plastic plate with a metal laminate that is structured into contact terminal pads, rewiring lines, and external contact surfaces. The fiber reinforcement gives this embodiment the advantage that, when packaging the electronic component in a plastic housing, the rewiring plate retains its dimensional stability and can therefore withstand the high injection pressure. This injection pressure is in the order of between 8 MPa and 15 MPa. The structured metal laminate is installed on the bottom side of the rewiring plate and is protected from metallization during the soldering of the external contacts by a solder resist layer. Only the external contact surfaces are kept clear of both the solder resist and the plastic compound until the external contacts are installed.
In another embodiment of the invention, the metal laminate consists of copper or a copper alloy. The advantage of this is that the metal laminate can be galvanically applied on the fiber-reinforced plastic of the rewiring plate, and copper represents a relatively inexpensive metal laminate relative to the material costs.
Because copper surfaces oxidize easily and are therefore suitable for neither bonding nor soldering, the contact terminal pads on which bond connections will be produced and the external contact surfaces onto which the external contacts will be soldered are respectively furnished with a bondable or solderable coating in another embodiment of the invention.
The inventive method for fabricating one of the above described embodiments of the above described electronic component includes the following steps: A first semiconductor chip is provided with contact surfaces on an active front side. A rewiring plate is provided with an oblong through-hole that forms a bond channel, and with a rewiring plane consisting of contact terminal pads, rewiring lines and external contact surfaces. The semiconductor chip is fastened on the rewiring plate such that the contact surfaces of the semiconductor chip are positioned in the through-hole of the rewiring plate. Bond connections are then produced between the contact surfaces on the semiconductor chip and the contact terminal pads on the rewiring plate. Lastly, the through-hole is filled with a plastic compound, embedding the bond connections.
The particular advantage of this inventive method is that compact electronic components can be reliably produced using the method.
According to an embodiment of the inventive method, an approximately uniform wire length is maintained in the installation of the bond connections with the bond wires on the long sides of the through-hole. This is associated with the advantage that stable and flat bond connections can be produced, which results in a flat electronic component.
In summary, the invention has the following aspects: In order to be able to provide the semiconductor chips, which are becoming increasingly smaller with the progress of miniaturization, and whose external contacts (e.g. contact bumps or the like for what are known as ball grid arrays) continue to remain the same size, with a reliable rewiring, the contact terminal pads on the rewiring plane must have a certain minimum size. Otherwise, it is difficult to contact the bonds, which can lead to a declining reliability of the contacts. The higher-density semiconductor chips require more conductive tracks inside the rewiring plane. In order to make sufficient space available for them, the contact surfaces of the semiconductor chip can be arranged in only one row (what is known as a single pad row), and the bond channel can be accordingly constructed narrowly.
In order to be able to construct sufficiently large contact terminal pads of the rewiring structure, the contact surfaces of the semiconductor chip are inventively arranged in one or two rows by section, i.e. in a combination of single and double pad rows. In non-critical regions where there is sufficient space available for placing the contact terminal pads, i.e. in central regions, the contact surfaces are arranged in two rows. This way, a large number of bond connections can be led on a relatively small space. On the other hand, in the extreme regions, the contact surfaces are arranged in only one row. The bond channel can accordingly be constructed narrower, and therefore sufficient area is left between the bond channel and the external contact surfaces (ball landing pads) for accommodating the conductive track structures.
This development does not require modifying the rewiring plate fabrication or the fabrication of the electronic components with semiconductor chips. A miniaturization of chips with suitable housings is possible without changing the technology and without extra costs.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electronic component with a semiconductor chip and fabrication method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.